Why are the seeds of this species difficult? Some species of the Poaceae family can produce a high proportion of empty seeds, which collectors and curators must take account of. The seeds have physiological dormancy, which can be overcome by performing delicate surgery to enable the embryo to grow.
Dactyloctenium aegyptium (Image: S. Wood, RBG Kew)
This species has Orthodox seeds - dry to 15-20% eRH and store at -20ºC, or as cool as possible.
Sow on agar, germination paper or sand and germinate under a constant temperature of 20 or 25ºC, or using an alternating temperature regime of 25/15 or 35/20ºC (with an 8/16hr photoperiod), depending on local climatic conditions. Perform a cut-test on any seeds that have not germinated, to check for empty seeds. All empty seeds are non-viable in germination tests.
The seeds of this species may be Physiologically Dormant. To overcome seed dormancy, excise the tissue near the root tip before germination.
If germination is low, try mimicking the seasonal patterns of the species' native habitat. Use a moist pre-chill or pre-heat treatment (depending on local climatic conditions) or a dry after-ripening treatment, before germinating the seeds on agar, germination paper or sand at their optimum temperature.
(Image: S. Wood, RBG Kew)
The fruit is a dry, indehiscent caryopsis (0.85-1.14 mm x 0.7-1.03 mm x 0.5-0.55 mm), without lemma and palea attached. The pericarp protects the seed. The fruit is yellow-orange in colour and spherical with lateral compression. The surface of the fruit has an irregular microsculpture with grooves and ridges. The seed configuration is anatropous and the embryo is basal-lateral and small in relation to the seed. The embryo is yellowish-white in colour.
The occurrence of empty seeds is common in wild-collected accessions of some Poaceae species. Empty seeds may have a normal seed coat but an absent or under-developed embryo, or limited storage tissue.
Accepted name: Dactyloctenium aegyptium (L.) Willd.
Synonyms: Eleusine aegyptica Desf.
Common name: Durban crow's foot grass
References and Links
- Baskin, C.C. and Baskin J.M. (1998). Seeds: ecology, biogeography, and evolution of dormancy and germination. Academic Press, USA.
- Black, M., Bewley, J.D. and Halmer, P. (2006). The Encyclopaedia of Seeds: science, technology and uses. CAB International, UK.
- Food and Agriculture Organization of the United Nations and International Plant Genetic Resources Institute (1994). Genebank Standards. FAO/IPGRI, Rome, Italy.
- AFPD (African Flowering Plants Database) - Conservatoire et Jardin Botaniques de la Ville de Genève, Switzerland, and South African National Biodiversity Institute, Pretoria, RSA: Dactyloctenium aegyptium.
- PROTAbase (Plant Resources of Tropical Africa) - Wageningen, Netherlands: Dactyloctenium aegyptium.
- SID (Seed Information Database) - Royal Botanic Gardens, Kew, UK: Dactyloctenium aegyptium.
- Tropicos - Missouri Botanical Garden, USA: Dactyloctenium aegyptium.